Alignment of differently sized printheads in a printer

ABSTRACT

An inkjet printer is disclosed with mixed print resolution capabilities. The printed dots have a high resolution monochrome component such as black and lower resolution components such as cyan, magenta and yellow. For increased throughput, a higher resolution black printhead has a wider swath. Various alignments between the printheads and printed dots are disclosed. In one embodiment, the top edges of the smaller color printheads are aligned in a scanning carriage at or near the top of the wider black printhead. In other embodiments, the bottom edges of the smaller color printheads are aligned at or near the bottom of the wider black printhead. In another embodiment, the small color printheads are centered with the wider black printhead.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation application of parent application Ser. No.08/399,398, filed Mar. 6, 1995, now U.S. Pat. No. 5,764,254 which is acontinuation-in-part of application Ser. No. 08/145,261, filed Oct. 29,1993, entitled MIXED RESOLUTION PRINTING FOR COLOR AND MONOCHROMEPRINTERS, by Donald G. Harris, et al.

This application also relates to the copending applications Ser. No.08/056,556, filed Apr. 30, 1993, now U.S. Pat. No. 5,408,746, entitledDATUM FORMATION FOR IMPROVED ALIGNMENT OF MULTIPLE NOZZLE MEMBERS IN APRINTER, by Jeffrey A. Thoman, et al., and Ser. No. 07/958,833, filedOct. 8, 1992, entitled PRINTHEAD WITH REDUCED INTERCONNECTIONS TO APRINTER, by Michael B. Saunders, et al., both owned by the assignee ofthis application and incorporated herein by reference.

BACKGROUND OF THE INVENTION

This invention relates generally to printers, and more specifically toprinting devices and techniques for monochrome and color printerscapable of achieving high quality resolution.

High quality printers are typically characterized by numbers indicatingtheir resolution in dots per inch (dpi). This resolution is usuallydescribed in the context of a two dimension coordinate system where onenumber indicates the resolution in the x-axis (as used herein, x-axismeans the carriage scan axis for a swath printer), and another numberindicates the resolution in the y-axis (as used herein, y-axis means themedia advance axis for a swath printer). Thus, a resolution of 300/300dpi generally indicates a carriage-scan axis resolution of 300 dots perinch and a media-advance axis resolution of 300 dots per inch. If only asingle dpi number is given, it is assumed the dpi in both axes areequal.

The resolution of a printhead is primarily determined by the actualprintout dot size as it appears in a printout.

Hewlett-Packard has developed a 600 dpi inkjet pen for producing a veryhigh resolution printout. One embodiment of this pen is described inHewlett-Packard's U.S. Pat. No. 5,278,584, by Brian J. Keefe, et al.,entitled INK DELIVERY SYSTEM FOR AN INKJET PRINTHEAD, incorporatedherein by reference. The nozzle array of this 600 dpi pen contains 300nozzles and prints a swath approximately one-half inch wide along thex-axis. Some of Hewlett-Packard's color printers will include a scanningcarriage housing the 600 dpi pen, containing black ink, as well as oneor more color inkjet pens. Currently these color inkjet pens have aresolution of 300 dpi and a width on the order of one-third inch.

The particular alignment of the 600 dpi and 300 dpi resolutionprintheads in the carriage as well as the particular alignment of theprinted high resolution dots and lower resolution dots can be selectedto achieve certain characteristics and advantages.

BRIEF SUMMARY OF THE INVENTION

In the preferred form, a scanning carriage in a color inkjet printerhouses a high resolution printhead for black (or monochrome) printingand one or more lower resolution printheads for color printing.

In one embodiment, the width of the color inkjet printhead(s) is lessthan the width of the black inkjet printhead. To allow the color inkmore time to dry on the paper before the paper is output from theprinter, the color printhead(s) are aligned near the edge of the widerblack printhead farthest from the paper outlet. Alternately, the colorprinthead(s) are aligned near the edge of the wider black printheadclosest to the paper outlet. This would allow the black ink to spendless time in the printing area, which can be hot or be subject to otherharsh conditions. Alternatively, the centers of the color printhead(s)are aligned towards the center of the wider black printhead. Thissymmetry can produce print quality advantages by balancing the benefitsobtained by the previous two alignments. This alignment also uses themore centrally located nozzles in the black pen, which inherentlyproduce better print quality.

Additionally, the nozzle arrangements, paper feed increments, and inkdrop firing frequency can be selected to provide various alignmentsbetween the larger color ink dots and the smaller black ink dots toachieve maximum ink coverage with a minimum of ink or to achieveadditional color shades.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a typical inkjet printer which can incorporate theapparatus and method of the present invention;

FIG. 2 shows a carriage having removable multi-color print cartridges,which can incorporate the apparatus and method of the present invention;

FIG. 3 shows an exemplary lower resolution color inkjet print cartridgeused in one embodiment of the invention;

FIG. 4 is a perspective view of a carriage incorporating one embodimentof the invention in an inkjet printer;

FIG. 5 is a top view of the carriage of FIG. 4;

FIG. 6 is a fragmentary view of the flex-circuit interconnect on thecarriage of FIGS. 4 and 5, with the interior carriage walls cut away;

FIG. 7 is a schematic block diagram of the print cartridges in oneembodiment of the invention;

FIG. 8 is a schematic bottom view as seen looking up from the mediashowing one alignment relationship of the nozzle arrays of FIG. 7;

FIG. 9 is a schematic view showing the use of a foam member foroperatively connecting a flex-circuit to a higher resolution blackinkjet cartridge;

FIG. 10 is an exploded view showing a flex-circuit frame portion of acarriage, with the foam spring member of FIG. 9 for assuring pressureconnection of a flex-circuit to a higher resolution black inkjetcartridge, and a metal spring member for assuring pressure connection ofa flex-circuit to lower resolution color inkjet cartridges;

FIG. 11 is a front view of the flex-circuit frame of FIG. 10;

FIG. 12 is a schematic diagram showing the relative resolution between a600 dpi printout of the black printhead and a 300 dpi printout of thecolor printheads in one embodiment of the invention;

FIGS. 13A-13D are schematic views as seen looking up from the mediashowing four different alignments between a high resolution nozzle arrayand one or more lower resolution nozzle array(s);

FIGS. 14, 15 and 16 are schematic views of single-plate nozzle arraysfor three different tricolor inkjet pens;

FIG. 17 is a schematic view of the nozzle arrays of three separate colorpens as positioned within the carriage of FIG. 2;

FIGS. 18-24 illustrate various possible alignments between printed highresolution dots and lower resolution dots.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

In a multiple pen printer, it is important to improve the output qualityof a printed page and increase the speed at which that output can beobtained as economically and simply as possible. In a printer mechanism,the output quality of a printed page is a function of printheadresolution. The higher the resolution the better the print quality.Also, in a swath printer employing a scanning carriage, the speed atwhich the output can be obtained is a function of the width of the swathwhich is covered by the printhead.

In current multi-pen printers, each pen has the same resolution andusually the same swath width. This means that all the supportingstructure, mechanics and electronics needs to be scaled up to supportthe resolution of the entire set of pens. All this hardware is moreexpensive than the hardware to support a multi-resolution, multi-swathwidth pen set where one pen is at the desired higher resolution andlarger width, and the other pens in the set are at a lower resolutionand smaller size.

One embodiment of the invention incorporates a high resolution inkjetpen and one or more lower resolution inkjet pen(s) in the same scanningcarriage in a printer. The higher performance pen can be used to improveoutput quality by enhancing certain key features that appear frequentlyin a printed page such as text. Such a pen also improves throughput bybeing able to print these frequent features faster. The other lowerperformance pens can be used for less frequent or less demandingfeatures such as graphics and color printing.

In the presently preferred embodiment of the invention disclosed herein,we have combined a 600 dpi 1/2 inch maximum print swath black pen withthree 300 dpi color pens each generating a maximum print swath ofapproximately 1/3 inch. The high performance black pen is typically usedfor printing text and other "black only" features, and thus the outputquality and throughput of these features is greater. It also improvesthe output quality of color graphics and color features by teaming withthe three lower performance color pens when printing color graphics orcolor features. The black component of the graphics, which is often alarge portion of color graphics content, is at a higher resolution andthus at a higher output quality level. The larger swath can then becombined with printing algorithms to improve the throughput of colorgraphics.

Even though the invention can be used in any printing environment wheretext and/or graphics are applied to media using monochrome and/or colorcomponents, the presently preferred embodiment of the invention is usedin an inkjet printer of the type shown in FIG. 1. In particular, inkjetprinter 10 includes an input tray 12 containing sheets of media 14 whichpass through a print zone, and are fed past an exit 18 into an outputtray 16. Referring to FIGS. 1-2, a movable carriage 20 holds printcartridges 22, 24, 26, and 28 which respectively hold yellow (Y),magenta (M), cyan (C) and black (K) inks. The front of the carriage hasa support bumper 30 which rides along a guide 32 while the back of thecarriage has multiple bushings such as 34 which ride along slide rod 36.The position of the carriage as it traverses back and forth across themedia is determined from an encoder strip 38 in order to be sure thatthe various ink nozzles on each print cartridge are selectively fired atthe appropriate time during a carriage scan.

In another embodiment printer, the color print cartridges 22, 24, and 26are replaced by a single tricolor cartridge having a nozzle plate suchas shown in FIG. 14, 15, or 16.

Referring to FIGS. 3-6, a 300 dpi color inkjet cartridge 40 having atab-circuit with a four column thirty-two pad electrical interconnect 42is removably installed in three chutes 44, 46, 48 of a unitary carriage50 (FIG. 4). A flex-circuit member 52 (FIG. 6) having three matchingsets of conductive pads 54, 56, 58 is mounted on flex-frame pins 60 foroperative engagement with the cartridge pads when the cartridge isinserted into its appropriate chute. An enlarged set of conductive pads62 covering a larger area, having a different layout, and constitutingan array of six columns totaling fifty-two conductive pads on theflex-circuit member is designed for operative engagement with cartridgepads on a 600 dpi black inkjet cartridge 64 (see FIG. 9).

The preferred structure and techniques for preventing mistakeninstallation of a 600 dpi black printhead in a color printhead chute, oralternatively the mistaken installation of a 300 dpi color printhead ina black printhead chute is described in the copending applicationsidentified above and incorporated by reference herein.

Because of the differently configured electrical interconnect on the 600dpi cartridge, and in order to avoid substantially changing the existingX/Y/Z datum configuration of the carriage, a unique interconnect schemeis employed. In that regard, the X-axis cartridge datums 65 engage theX-axis carriage datums 66, and the Y-axis cartridge datums 67 engage theY-axis carriage datums 68, and the Z-axis cartridge datums 69 engage theZ-axis carriage datums 70 in a manner more fully described in thecopending applications identified above and incorporated by referenceherein.

As best shown in FIGS. 9-11, a spring assembly including a backing sheet74, a plate 76 and a gimbal spring 78 are sized for fitting intoapertures 80 of flex-circuit frame 82 to assure proper electricalinterconnection for the three color cartridges.

A unique spring assembly for the 600 dpi cartridge interconnect includesa unitary resilient foam member 84 which fits in a seat 86 which islarger than the aperture 80. A mounting peg 88 fits into matching hole90 which along with bottom and lower ledges 91, 93 and upper side andtop ledges 92, 94 hold the foam member in proper position to assureoperative engagement across the electrical interconnect.

FIGS. 7-8 show one possible mounting relationship between a 300 dpinozzle array 96 of the color printheads and a 600 dpi nozzle array 98 ofthe black printhead. Control circuitry 99 (including a multiplexer) onthe substrate enables the three hundred firing resistors of the blackprinthead to be controlled through fifty-two electrical interconnectpads, and similarly enables all one hundred firing resistors of eachcolor printhead to be controlled through thirty-two electricalinterconnect pads.

FIG. 12 schematically shows the difference between the 300 dpi printoutproduced by the color pens (i.e., pen cartridges) and the 600 dpiprintout of the black pen of the preferred embodiment described herein.The type of paper used, along with other well known factors, affect inkbleed. Therefore, the diameters of the actual printed dots in FIG. 12will vary.

Of course, it would be possible to incorporate different combinations ofresolution in different printheads wherein the resolution difference maybe arbitrary, depending on the printheads available and alreadydeveloped, or wherein the resolution difference may be decimally related(300 dpi with 400 dpi; 300 dpi with 450 dpi, etc.) or fractionallyrelated (e.g., 20% greater resolution, 30% greater resolution, etc.). Inthat regard, the invention can be implemented with any of the existinginkjet cartridges which are currently available, with the best resultsoccurring with printheads in the range of 180 dpi or greater.

Although FIGS. 8 and 12 show a preferred embodiment of the alignmentbetween a high resolution nozzle array and a lower resolution nozzlearray and a preferred embodiment of the alignment between the highresolution printed dots and the lower resolution printed dots, otheralignments are possible and have particular advantages.

FIGS. 13A, 13B, and 13C illustrate three different alignments between aone-half inch, 600 dpi black inkjet pen 110 and one or more color inkjetpens 112, 112', 112" when these pens 110, 112, 112', 112" are housed ina single carriage. Only the nozzle array faces are illustrated forsimplicity.

If a tricolor (CMY) pen is used, then only one inkjet pen 115, 116, or117 (FIGS. 14-16) need be used with the black inkjet pen 110. In theembodiments of FIGS. 13A-13D, three separate color pens 112, 112', 112"are employed when tricolor pens are not used.

FIGS. 14, 15, and 16 show three different embodiments of a printheadnozzle array face 115, 116, and 117, respectively, for such a tricolorinkjet pen having three separate ink compartments for the cyan, magenta,and yellow ink. Identified in FIGS. 14-16 are the three sets of nozzlesin the nozzle array face for the cyan (C), magenta (M), and yellow (Y)ink. The nozzles for each of the colors may be vertically aligned as inFIG. 14, staggered as in FIG. 15, or horizontally aligned as in FIG. 16.Two rows of offset nozzles 118 are provided for each color to provide ahigh vertical density of dots. A printer incorporating a tricolorcartridge may resemble that of FIG. 1 except that cartridges 22, 24, and26 would be a single tricolor cartridge alongside the black inkjetcartridge 28.

FIG. 17 illustrates the nozzle arrays of three separate color pens 120,121 and 122 when installed in the carriage 50 of FIG. 4. Pen 120 may bea cyan pen, pen 121 may be a magenta pen, and pen 122 may be a yellowpen, as also illustrated in FIG. 2, but the order of pens is not verysignificant to this invention.

In FIG. 13A, the tops of the printheads of the color pens 112, 112',112" are positioned near or aligned with the top of the printhead of theblack pen 110 so as to be farther from the paper outlet or outputrollers. The direction of paper transport is shown by arrow 124. Thisalignment allows the color ink to be placed on the paper farther fromthe output rollers so that the color ink is given more time to drybefore the paper is ejected by the output rollers. One contrastingexample of the positioning of printheads relative to the output rollerof a color printer is shown in U.S. Pat. No. 5,376,958, entitledSTAGGERED PENS IN COLOR THERMAL INK-JET PRINTER, by Brent W.Richtsmeier, et al., assigned to the present assignee and incorporatedherein by reference. The concepts described herein may be used inconjunction with that printer or any other printer. The relativealignments shown in FIG. 13A provide the above-mentioned benefitirrespective of the actual distance from the nozzle arrays to the outputrollers.

FIG. 13B shows an embodiment where the bottoms of the printheads of thecolor ink jet pens 112, 112', 112" are positioned near or aligned withthe bottom of the printhead of the black inkjet pen 110 so as to benearer the paper output rollers. This allows the ink from the black pen110 to spend less time in the printing area before the paper is ejected.This is desirable since the printer area can be at a high temperature orexperience other harsh conditions.

In FIG. 13C, the centers of the printheads of the color inkjet pens 112,112', 112" are aligned near or at the center of the printhead of theblack inkjet pen 110. This would generally cause the characteristics ofthe paper to be symmetrical with respect to the centers of the pens 110and 112, 112', 112". This may result in print quality advantages bybalancing the benefits obtained by the previous two alignments. Thisalignment also uses the more centrally located nozzles in the black pen,which inherently produce better print quality. The alignment of pens 110and 112, 112', 112" may also be off from center to variable degrees toachieve the best printing results. For example, the dimension of A inFIG. 13C may be 2 or 3 times the dimension of B or vice versa.

In FIG. 13D, a high resolution black pen 110 has the same printhead sizeas the printheads of the lower resolution color pens 125, 125', 125".The edges of the printheads of pens 110 and 125, 125', 125" are aligned.One drawback of the embodiment of FIG. 13D is that color printheadshaving the same width as the printhead of the black pen 10 may not beavailable.

In a preferred embodiment, the high resolution nozzle array has aone-half inch swath and 300 nozzles (150×2 offset columns), and the inkdrop volume for each nozzle is approximately 35 picoliters. The inkreservoir for this high resolution pen contains approximately 42milliliters of black ink. Color ink may also be used.

In one embodiment of a tricolor pen, having a nozzle plate such as thatshown in either FIGS. 14, 15, or 16, the ink drop volume for each nozzleis approximately 30 picoliters per drop. An ink reservoir for each ofthe three colors in the tricolor pen may contain approximately 19.1milliliters of ink. Each color is in fluid communication with 64 nozzlesin a single printhead.

In a preferred embodiment of each individual color pen 120, 121, or 122illustrated in FIG. 17, the ink drop volume for each nozzle isapproximately 104 picoliters, and the ink reservoir holds approximately42 milliliters of ink. Each printhead contains approximately 104 nozzlesat a dpi of 300.

In addition to the consideration being paid to the alignments betweenthe color inkjet printheads and the black inkjet printhead, thealignment between the individual dots printed by the black pen 110 andthe color pen or pens 112, 112', 112" may also be selected to providethe desired print characteristics.

FIGS. 18-22 illustrate various alignments between the high resolutiondots, having diameters of about 1/600 inch, and the lower resolutiondots, having diameters of about 1/300 inch. Ink bleed may cause the inkfrom adjacent dots to merge. The dots in FIGS. 18-22 are shown separatedfor clarity. The paper transport direction is assumed to be downwardwith respect to the page, and the pen scan direction is perpendicular tothe paper transport direction.

In FIG. 18, the centroid 130 of a cluster of four high resolution dots132 is aligned with the centroid 134 of a single lower resolution dot136. One goal is to maximize the ink coverage on the page while at thesame time minimizing the amount of ink put down on the page. Thealignment of dots in FIG. 18 comes close to, if not achieves, this goal.In one particular application, the centroid 134 of the lower resolutiondot 136 may overlap the centroid 130 of a cluster of four highresolution dots 132. Such an overlap is shown. This may be desirable forachieving particular colors or print characteristics. Also, one or morecolumns of the high resolution dots 132 may be printed between columnsof the lower resolution dots 136. Additionally, a lower resolution dot136 may be completely surrounded by higher resolution dots 132 as wouldbe the case if a single lower resolution dot 136 were placed in themiddle of the array of high resolution dots 132 shown in FIG. 18.

FIG. 19 illustrates another dot alignment where the lower resolutiondots 136 are shifted up or down one-half of a high resolution dot 132diameter. The overlap of a lower resolution dot 136 and four highresolution dots 132 is shown.

FIG. 20 illustrates another dot alignment where a centroid of a lowerresolution dot 136 may be aligned with the centroid of a high resolutiondot 132 or aligned between two high resolution dots 132. The lowerresolution dot 136 may print directly over a high resolution dot 132 orpartially over a high resolution dot 132, as illustrated.

In FIGS. 18-20, four high resolution dots 132 are placed around theircentroid 130 at 45 from the x and y axis lines. Four high resolutiondots 132 may also be placed along the 90 axis lines, as shown in FIG.21. Such an arrangement of high resolution dots 132 may be created byeither modifying the arrangement of nozzles in the nozzle array of aninkjet pen (or tilting the pen) to produce the dot arrangement of FIG.21 in a single swath or by modifying the energization speed of theinkjet firing resistors in combination with reducing the incrementalsteps of the paper. The mixed resolution dot alignments of FIG. 21present certain advantages in graphics applications. A cluster of lowerresolution dots 136 may either have the diamond pattern of FIG. 21 orthe square pattern of FIGS. 18-20.

Other mixed dot resolutions are also contemplated, such as 3 to 1resolutions or 4 to 1 resolutions, producing either a nine dot clusteror a sixteen dot cluster for every single lower resolution dot.

FIGS. 22-24 illustrate other alignments of high and lower resolutiondots.

In FIG. 22, adjacent columns of high resolution dots 132 are staggered,and a centroid of a cluster of four high resolution dots 132 is alignedwith a centroid of a lower resolution dot 136.

In FIG. 23, a similar arrangement is shown except that the lowerresolution dots 136 are shifted downward by one half of a higherresolution dot 132 diameter.

In FIG. 24, variations of the high resolution dot 132 patterns and lowerresolution dot 136 patterns are shown to illustrate the variouscombinations of alignments which may be obtained.

Any combination of high resolution and lower resolution dots maydirectly overlap to produce various colors or shades or more intensecolors. The black, high resolution dots 132 may be printed during thesame scan as the lower resolution dots 136 or during a different scan toreduce ink bleed and to otherwise enhance print quality.

The dot alignments of FIGS. 18-24, or a combination of the alignments,may be used to maximize the ink coverage on a page while minimizing theamount of ink put down. Dot alignments may even be changed duringprinting or between print jobs as desired. The selection of a particulararrangement may depend on the expected ink bleed and ink characteristicsas well as the particular image being printed.

While particular embodiments of the present invention have been shownand described, it will be obvious to those skilled in the art thatchanges and modifications may be made without departing from thisinvention in its broader aspects and, therefore, the appended claims areto encompass within their scope all such changes and modifications asfall within the true spirit and scope of this invention.

What is claimed is:
 1. A mixed resolution printer comprising:a frame forholding a medium for being printed upon in a print zone; a carriagesupported on said frame and movable across said print zone during ascan; a first printhead mounted on said carriage and including a firstarray of nozzles for printing a swath of black ink, said first printheadhaving a first print resolution and a first width parallel to adirection of movement of said medium through said print zone, said firstprinthead having a top edge facing opposite said direction of movementof said medium and a bottom edge facing said direction of movement ofsaid medium, said first array of nozzles being disposed between said topand bottom edges; a second printhead mounted on said carriage parallelto said first printhead, said second printhead including a second arrayof nozzles for printing a swath of color ink, said second printheadhaving a second print resolution lower than said first print resolutionand a second width shorter than said first width, said second printheadhaving a top edge facing opposite said direction of movement of saidmedium and a bottom edge facing said direction of movement of saidmedium, said second array of nozzles being disposed between said top andbottom edges, a third printhead mounted on said carriage and disposedbetween said first and second printheads, said third printhead beingidentical to said second printhead for printing a swath of a secondcolor ink, wherein an edge of said second printhead and an edge of saidthird printhead are substantially aligned with an edge of said firstprinthead, such that a maximum print swath created by said firstprinthead at least partially overlaps a maximum print swath created bysaid second and third printheads during a single scan of said carriageacross said medium.
 2. The mixed resolution printer of claim 1 whereinsaid top edge of said second printhead, is substantially aligned withsaid top edge of said first printhead.
 3. The mixed resolution printerof claim 1 wherein said bottom edge of said second printhead issubstantially aligned with said bottom edge of said first printhead. 4.The mixed resolution printer of claim 1 wherein said second printheadprints ink including a color component selected from a group consistingof cyan, magenta, and yellow.
 5. The mixed resolution printer of claim 1wherein said second printhead prints a plurality of ink colors.
 6. Themixed resolution printer of claim 1 wherein said second printhead printsa single first color, said printer further comprising a third printheadidentical to said second printhead and positioned adjacent said secondprinthead, wherein said third printhead prints a single second color. 7.The mixed resolution printer of claim 1, wherein said printer is aninkjet printer.
 8. The mixed resolution printer of claim 1 furthercomprising inks supplied to said first printhead, said second printhead,and said third printhead.
 9. A method performed by a color printercomprising the step of:scanning a carriage across a print zone of amedium to be printed upon, said carriage supporting a first printhead, asecond printhead, a third printhead, and a fourth printhead in aside-by-side relationship for composite printing by said firstprinthead, said second printhead, said third printhead, and said fourthprinthead on the medium in said print zone; and supplying energizingsignals to said first printhead, said second printhead, said thirdprinthead, and said fourth printhead as said carriage is scanning andsaid medium is held stationary so that said first printhead prints amaximum print swath having a top and a bottom and said second printhead,said third printhead, and said fourth printhead each print maximum printswaths, each maximum print swath having a top and a bottom, wherein saidmaximum print swath printed by said first printhead at least partiallyoverlaps said maximum print swaths printed by said second printhead,said third printhead, and said fourth printhead during scanning of saidcarriage across said medium, said first printhead printing black ink andhaving a first print resolution, a first width parallel to a directionof movement of said medium through said print zone, a top edge facingopposite said direction of movement of said medium, and a bottom edgefacing said direction of movement of said medium, said second printhead,said third printhead, and said fourth printhead printing color inks andhaving a second print resolution lower than said first print resolution,a second width shorter than said first width, a top edge facing oppositesaid direction of movement of said medium, and a bottom edge facing saiddirection of movement of said medium, wherein said step of supplyingenergizing signals causes said top or bottom of each of said maximumprint swaths created by said second printhead, said third printhead, andsaid fourth printhead to be aligned with said top or bottom,respectively, of said maximum print swath created by said firstprinthead.
 10. The method of claim 5 wherein said second printhead, saidthird printhead, and said fourth printhead print ink including colorcomponents selected from a group consisting of cyan, magenta, andyellow.
 11. The method of claim 5 wherein said second printhead, saidthird printhead, and said fourth printhead are located in a single printcartridge.
 12. The method of claim 5 wherein said second printhead, saidthird printhead, and said fourth printhead are each located in aseparate print cartridge.
 13. The method of claim 5 wherein said step ofsupplying energizing signals causes said top of each of said maximumprint swaths created by said second printhead, said third printhead, andsaid fourth printhead to be aligned with said top of said maximum printswath created by said first printhead.
 14. The method of claim 5 whereinsaid step of supplying energizing signals causes said bottom of each ofsaid maximum print swaths created by said second printhead, said thirdprinthead, and said fourth printhead to be aligned with said bottom ofsaid maximum print swath created by said first printhead.